The present invention relates to a pressure-sensitive cleaning sheet, a method of using the same, an image-forming material having a cleaning part, and a method of cleaning an image-forming apparatus. These are useful for, e.g., the cleaning of the magnetic reading parts and magnetic-card transport parts of apparatuses accepting various magnetic cards, such as reader/writers for rewritable cards and magnetic-card public telephones, the cleaning of the thermal printing head parts of thermal transfer printers, and the cleaning of the thermal heads and/or transport rollers of various recorders such as thermal recorders, printers for newspapers and journals, OA apparatus printers, and photographic printers.
In magnetic-card readers, for example, the magnetic reading part and the magnetic-card transport part (belts and rollers) are gradually fouled due to foreign matters adherent to magnetic cards, such as sebaceous or oily secretions from fingers and dust particles. The fouling may finally results in a reading failure. In order to avoid this, the magnetic reading part and the magnetic-card transport part need to be cleaned periodically.
In thermal transfer printers, there are cases where the thermal head part is fouled by the ink ribbon to cause blurring, etc. The thermal head part hence needs to be cleaned periodically.
Image-forming apparatuses such as the printers of word processors and facsimile telegraphs and bar code printers employ image-forming materials such as ink ribbons and toners. For example, in the image-forming apparatuses employing an ink ribbon, in which the thermal head should be brought into contact with the ink ribbon, there is a problem that foreign matters adhere to the heating part of the thermal head and accumulate thereon as the number of contacts increases, resulting in troubles in image formation.
The image-forming apparatuses employing heat-sensitive recording media have the same troubles.
The transport rollers of the above image-forming apparatuses also are fouled by the adhesion of dust particles present in the surrounding atmosphere and of paper dust, etc., resulting in transport troubles. In printers for newspapers or journals, photographic printers, and the like, which frequently employ paper as an image-receiving material, there is a problem that paper dust adheres to the rolls and accumulates thereon as the number of times of use increases, resulting in transport troubles.
At present, there is no sufficient measure to overcome the above problems. In case of troubles, it has been necessary to stop the apparatus to disassemble and clean the same. However, the cleaning requires much time, during which the apparatus cannot be used, causing great inconvenience.
Prior art cleaning techniques proposed so far include: a method in which a cleaning sheet of any of various card sizes which comprises a substrate sheet having a mere pressure-sensitive adhesive layer on one or both sides thereof is inserted into an apparatus accepting magnetic cards, whereby dust particles and other foreign matters adherent to the magnetic reading part and the magnetic-card transport part are transferred to the pressure-sensitive adhesive surface; and a method in which a cleaning sheet comprising a substrate sheet and a liquid-absorbing layer, e.g., a cloth or a nonwoven fabric, disposed on one or both sides of the substrate through a pressure-sensitive adhesive layer is inserted into an apparatus accepting magnetic cards after the liquid-absorbing layer is impregnated with a solvent such as acetone or an alcohol or with water, whereby dust particles and other foreign matters adherent to the magnetic reading part and the card transport part are wiped away with the solvent-impregnated layer of the cleaning card (see, for example, JP-A-U-5-90608). (The term xe2x80x9cJP-A-Uxe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese utility model applicationxe2x80x9d.)
However, cleaning with the above-described cleaning card impregnated with a solvent is disadvantageous in that the working atmosphere becomes worse due to solvent vapor and the use of a solvent may damage the magnetic reading part or transport part or may cause other troubles.
In contrast, cleaning with the above-described pressure-sensitive cleaning sheet eliminates those troubles. However, if a strongly tacky pressure-sensitive adhesive is used for heightening the cleaning efficiency, there are problems, for example, that transfer of the pressure-sensitive adhesive to the surfaces to be cleaned (so-called adhesive transfer) and winding of the cleaning sheet around a transport roller are apt to occur, and that smooth cleaning is difficult since the cleaning sheet is apt to be caught due to its tackiness at the magnetic-card insertion opening or takeout opening in an apparatus accepting magnetic cards. On the other hand, if a weakly tacky pressure-sensitive adhesive is used, the efficiency of the removal of foreign matters including dust particles decreases inevitably, so that the pressure-sensitive cleaning sheet should be repeatedly inserted a larger number of times, unavoidably resulting in a decrease in the efficiency of cleaning.
In the case of conducting cleaning with any of these prior art cleaning sheets, the cleaning sheet is actually used only when the apparatus has come not to work. Thus, the prior art techniques do not provide a drastic measure.
Still another cleaning technique has been proposed, e.g.,in JP-A-U-64-30259 and JP-A-63-8136 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d), in which a body to be transported, such as ink sheets, having a pressure-sensitive adhesive layer for cleaning as a part thereof is used. However, this prior art cleaning technique also has the same problems as the above, and is still unsatisfactory.
A first object of the present invention is to provide a pressure-sensitive cleaning sheet with which cleaning can be easily and smoothly conducted highly efficiently while satisfactorily preventing adhesive transfer. Specifically, the object is to provide a pressure-sensitive cleaning sheet with which fouling substances can be easily removed, for example, from the magnetic reading part or magnetic-card transport part of an apparatus accepting magnetic cards and from the thermal head part of the printing part of a thermal transfer printer.
A second object of the present invention is to provide a roll-form image-forming material which has a specific cleaning part and with which not only fouling substances can be removed from an image-forming apparatus without stopping the same, but the number of times of disassembling/cleaning can be reduced.
The present invention provides a pressure-sensitive cleaning sheet comprising a substrate, a pressure-sensitive adhesive layer formed on one or both sides of the substrate, and a porous screen disposed on the pressure-sensitive adhesive layer, the cleaning sheet being substantially non-tacky when the cleaning sheet surface is kept in a non-pressed state, under which the porous screen is projecting from the surface of the pressure-sensitive adhesive layer, and the cleaning sheet exhibiting tackiness when the cleaning sheet surface is kept in a pressed state, under which the pressure-sensitive adhesive layer appears on the sheet surface through the openings of the porous screen to thereby have a surface which is on almost the same level as the surface of the porous screen.